RESUMO
The COVID-19 pandemic prompted rapid vaccine development and deployment worldwide. Despite widespread vaccination efforts, understanding the effectiveness of vaccines in hospitalized patients remains a critical concern. This retrospective cohort study, conducted at a tertiary healthcare centre in Serbia, tracked patients hospitalized during different waves of COVID-19 variants-Alpha, Delta, and Omicron. Data collection included demographics, comorbidities, symptoms, and vaccination status. Among 3593 patients, those with prior exposure to COVID-19 cases or hospital treatment showed higher positivity rates. Symptom prevalence varied across waves, with coughs persisting. Patients without chronic diseases were more frequent among those testing negative. Vaccine effectiveness varied, with Sinopharm demonstrating a 45.6% effectiveness initially and Pfizer-BioNTech showing an effectiveness of up to 74.8% within 0-84 days after the second dose. Mixed-dose strategies, notably Sinopharm as a primary dose followed by a Pfizer-BioNTech booster, suggested increased protection. Despite substantial vaccination availability, a significant portion of hospitalized patients remained unvaccinated. This study underscores the dynamic nature of vaccine effectiveness and advocates for booster strategies to address evolving challenges in combating COVID-19, particularly in hospitalized patients.
RESUMO
(1) Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its resulting coronavirus disease 2019 (COVID-19) has caused a fast-moving pandemic. Diagnostic testing, aimed to identify patients infected with SARS-CoV-2, plays a key role in controlling the COVID-19 pandemic in different populations. (2) Methods: This retrospective cohort study aimed to investigate predictors associated with positive polymerase chain reaction (PCR) SARS-CoV-2 test results in hospitalized patients, healthcare workers (HCWs), and military personnel (MP) during 2020, before the widespread availability of COVID-19 vaccines. Persons with a positive test result were compared with persons with a negative test result in three cohorts during the study period. (3) Results: A total of 6912 respondents were tested, and 1334 (19.3%) of them had positive PCR SARS-CoV-2 test results. Contact with a known COVID-19 case within 14 days (p < 0.001; OR: 1.48; 95% CI: 1.25-1.76), fever (p < 0.001; OR: 3.66; 95% CI: 3.04-4.41), cough (p < 0.001; OR: 1.91; 95% CI: 1.59-2.30), headache (p = 0.028; OR: 1.24; 95% CI: 1.02-1.50), and myalgia/arthralgia (p < 0.001; OR: 1.99; 95% CI: 1.65-2.42) were independently associated with positive PCR SARS-CoV-2 test results in the cohort of MP. Furthermore, fever (p < 0.001; OR: 2.75; 95% CI: 1.83-4.13), cough (p < 0.001; OR: 2.04; 95% CI: 1.32-3.13), headache (p = 0.008; OR: 1.76; 95% CI: 1.15-2.68), and myalgia/arthralgia (p = 0.039; OR: 1.58; 95% CI: 1.02-2.45) were independently associated with positive PCR SARS-CoV-2 test results in the cohort of HCWs. Moreover, independent predictors of positive PCR SARS-CoV-2 test results in hospitalized patients were contact with a known COVID-19 case within 14 days (p < 0.001; OR: 2.56; 95% CI: 1.71-3.83), fever (p < 0.001; OR: 1.89; 95% CI: 1.38-2.59), pneumonia (p = 0.041; OR: 1.45; 95% CI: 1.01-2.09), and neurological diseases (p = 0.009; OR: 0.375; 95% CI: 0.18-0.78). (4) Conclusions: According to data gathered from cohorts of hospitalized patients, HCWs, and MP, before the widespread availability of COVID-19 vaccines in Serbia, we can conclude that predictors of positive PCR SARS-CoV-2 test results in MP and HCWs were similar. Accurate estimates of COVID-19 in different population groups are important for health authorities.
